The present invention relates to cigarette makers and analogous machines for forming and processing streams of fibrous material, and more particularly to improvements in apparatus for facilitating the detection and removal of foreign objects from fibrous material, such as batches of tobacco shreds in the distributor of a cigarette making machine.
It is known to provide the distributor of a cigarette making machine with a conveyor which draws tobacco shreds from a magazine and cooperates with a paddle wheel in order to ensure that the next station of the distributor will receive tobacco shreds at a more or less constant rate. Reference may be had, for example, to commonly owned U.S. Pat. No. 4,185,644 and to numerous other patents and pending patent applications of the assignee of the present application.
The presence of relatively small metallic objects in the continuous or intermittent flow of tobacco particles which is formed and advanced in the distributor of a cigarette maker is normally detected by a magnetic roller which is adjacent to the path of movement of tobacco particles toward the cigarette rod forming station However, the flow of tobacco particles in the magazine of the distributor (also known as hopper in Great Britain and in certain other English-speaking countries) is equally likely to carry other foreign objects which may but need not contain metallic substances. For example, the magazine can receive (at randomly spaced intervals) fragments of cloth, fragments of paper and/or other rather bulky foreign objects which can interfere with proper operation of the machine and whose belated detection can result in the making of thousands of defective articles and/or in extensive damage to the distributor. For example, a piece of cloth or other textile material caught by the carding and/or other protruding parts on the belt conveyor which draws tobacco shreds from the magazine of the distributor can cause deformation and/or breakage of the protruding parts which, in turn, necessitates the removal and replacement of the entire conveyor with attendant huge losses in the output of a machine which is designed to turn out up to and in excess of 8000 rod-shaped articles per minute. Moreover, even short-lasting stoppage of a cigarette maker necessitates the idling of an entire production line which can include a filter rod making machine, a packing machine, a carton filling machine and/or others.